Square root.
5^2 = 25 so sqrt25 = 5
He used 12 gallons of white paint.
Because 20 divided by 5 = 4. Meaning that 4 gallons is one part.
4 x 5 = 20
4 x 3 = 12
2l + 2w = P
2(10) + 2w = 44
20 + 2w = 44
2w = 24
w = 12
The width is 12 units.
1) 5:10 = 1:2
2) 25:30 = 20:24
3) 5:4 = 10:8
4) 1:3 = 3:9
5) 7:1 = 63: 9
6) 45:18 = 5:2
7) I can't see it (it was cut off in the picture)
8) 2:14 = 1:7
Hope this helped